This invention relates to a method and apparatus for extracting horizontal underground pipe which is particularly but not exclusively designed for use in the removal of existing underground water pipes in a manner in which leaves a usable hole in which new water pipes can be installed.
In many cities and areas, underground water pipes have been in place for many years and have now reached the stage where serious corrosion is taking place causing many breaks and slow water losses. When such water pipes reach the end of a normal working life, therefore, it is necessary to remove the pipes and generally to replace them with new pipe which can transport the water to the existing outlets.
There are two commonly used methods for removing such water pipes. In a first method a channel is excavated directly down to the pipe along the full length of the existing pipe so that the pipe can simple be lifted from the channel and a replacement pipe laid along the channel in place of the first. This method is extremely time consuming and therefor costly, and also has a severe disadvantage particularly in areas where the water pipes need to be buried at a deep level wherein cave-ins of the excavated channel can be very dangerous for the operatives. Furthermore, the existence of various obstacles such as driveways, trees and roads in the path of the pipe can cause great inconvenience and substantially increase the cost of the excavation.
In a second commonly used method, particularly where obstacles are present, a shaft or hole is dug at either end of the obstructed area and a cable passed through the existing pipe. A backhoe is then used to pull out the existing pipe into the excavated shaft, whereupon the pipe is broken into pieces using sledgehammers. This method is normally only used in situations where there are obstructions in the path of the normal excavated channel and is therefor only used to remove short lengths of pipe, for example 10 to 25 feet in length. In view of the crude techniques employed, this method of removing and breaking existing water pipe is more time consuming and costly than the complete excavation method and is therefor only used where obstacles make the excavation method impractical.